1. Field of the Invention
The present invention is directed generally to systems and methods for monitoring macular and retinal diseases, and more particularly to providing programs or video games for testing or mapping macular visual acuity.
2. Description of Related Art
Age-related macular degeneration (AMD) is a leading cause of blindness. It is a degeneration of the macula (central portion of the retina) that is associated with age. The progress of AMD is generally slow in the dry form of the disease. However, in a portion of affected eyes the wet form of the disease can arise, where abnormal growth of new vessels and scar tissue under the retina can lead to rapid loss of vision. The abnormal growth of new blood vessels is called neovascularization and therefore wet AMD is also called neovascular AMD. Fortunately, neovascular AMD can now be treated by intravitreal injection of anti-angiogenic medications, which often reverse the loss of vision. However, early detection of neovascular AMD is needed for treatment to begin in time before the loss of vision becomes permanent.
The Amsler chart is a long standing standard test for AMD that can detect distortions in vision caused by neovascular AMD. However, its sensitivity in detecting neovascular AMD is much lower than a newer test called the preferential hyperacuity perimeter (PHP), where the Vernier acuity of the pericentral area is mapped. Vernier acuity is defined by the resolution with which an eye can detect the relative location of two visual stimuli, such as the relative displacement of two line segments. Vernier acuity is also called hyperacuity because its threshold of perception is several times finer than the eye's ability to perceive spatial separation between features in a standard visual acuity target, such as the opening in the Landolt C or line separations in the tumbling E or standard optotypes. Compared to normal acuity, Vernier acuity is relatively unaffected by degradation of retinal image quality by cataract and other age-related conditions. Therefore it is a good test to detect retinal abnormalities in an elderly population.
Currently PHP testing is performed using a special device that is installed in the clinic of retina specialists and ophthalmologists. It is administered by trained personnel. Therefore it is not accessible to AMD patients for frequent self-testing. There is a need for home test that can be self-administered by subjects who has AMD or are at risk for AMD, so that the test can be performed frequently (daily or weekly). The test should preferably be in the form of a game that can maintain player interest. And the resulting preferential hyperacuity map should preferably be automatically analyzed by a computer and transmitted electronic to a physician who monitors the patient's eye health.